/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package javax.servlet;

/**
 * This is the event class for notifications of changes to the attributes of the
 * servlet request in an application.
 *
 * @see ServletRequestAttributeListener
 * @since Servlet 2.4
 */
public class ServletRequestAttributeEvent extends ServletRequestEvent {
	private static final long serialVersionUID = 1L;

	private final String name;
	private final Object value;

	/**
	 * Construct a ServletRequestAttributeEvent giving the servlet context of
	 * this web application, the ServletRequest whose attributes are changing
	 * and the name and value of the attribute.
	 *
	 * @param sc      the ServletContext that is sending the event.
	 * @param request the ServletRequest that is sending the event.
	 * @param name    the name of the request attribute.
	 * @param value   the value of the request attribute.
	 */
	public ServletRequestAttributeEvent(ServletContext sc,
	                                    ServletRequest request, String name, Object value) {
		super(sc, request);
		this.name = name;
		this.value = value;
	}

	/**
	 * Return the name of the attribute that changed on the ServletRequest.
	 *
	 * @return the name of the changed request attribute
	 */
	public String getName() {
		return this.name;
	}

	/**
	 * Returns the value of the attribute that has been added, removed or
	 * replaced. If the attribute was added, this is the value of the attribute.
	 * If the attribute was removed, this is the value of the removed attribute.
	 * If the attribute was replaced, this is the old value of the attribute.
	 *
	 * @return the value of the changed request attribute
	 */
	public Object getValue() {
		return this.value;
	}
}
